James f



(ModeL) J. P. WELCH. WORM GEAR.

w No. 486,204. Patented Nov. 15, 1892..

NORRIS PETERS 90 mom-Lima, wAsnmamu, a c

UNITED STATES PATENT OFFICE,

JAMES F. WELCH, OF BROOKLYN, NEW YORK, ASSIGNOR TO THE GLEN COVE MACHINE COMPANY, LIMITED, OF SAME PLACE.

WORM-GEAR.

SPECIFICATION forming part of Letters Patent No. 486,204, dated November 15, 1892.

Application filed February 18, 1892. Serial No. 421,938- (Model-l To all whom it may concern.-

Be it known that I, JAMES F. WELCH, of Brooklyn, in the county of Kings and State of New York, have invented a new and useful Improvementin Worm-Gears, of which thefollowing is a specification.

My invention relates to an improvement in worm-gear, with the object in view of obtaining an increased area of contact between the teeth of the Worm and gear-Wheel.

A practical embodiment of my invention is represented in the accompanying drawings, in which Figure 1 is a view of the worm inside elevation, showing in dotted lines a section of the wormwheel in engagement therewith. Fig.2 is a view of the worm-wheel in side elevation, and-Fig. 3 is a view of the worm-wheel in edge or face elevation.

The outer faces of the teeth on the worm, taken in a plane extending through the longitudinal axis of the Worm, are in the circumference of a circle corresponding to the circumference of the wormwheel at the base of the teeth in a central plane transversely to its axis, and the faces of the teeth on the worm-wheel are formed on a wind corresponding to the wind of the worm and are concave on a curve corresponding to the curve of the worm-shaft between its teeth, while the bottoms of the spaces between the teeth on the worm-wheel are concave on a curve corre-. sponding to a curve of the faces of the teeth on the worm. The contact sides of the teeth on the worm continuously change their positions relatively to the axis of the worm-shaft throughout their length to conform to the continuously-changing positions of the teeth on the rotating worm-wheel, and the contact sides of the teeth on the worm-wheel have a wind or compound curve corresponding to the sides of the teeth on the worm, having a genwith which the worm engages, gradually changes its position relatively to the axis of the worm-shaft, and my present invention provides for such a structure of the wormtooth that its contact side a for example,

will adjustitself t S tIElTcohStantIy-Varying positions of the tooth on the worm-wheel and thereby exert a constant pressure upon such tooth during its travel through a considerable portion of its arc. The teeth b on the worm- Wheel have a shape which conforms to the space between two successive teeth of the worm, leaving a little space for clearance. 1

The method of 'cutting the teeth upon the worm and worm-wheel and apparatus for doing it form the subject-matter of another application, filed by me, of even date herewith, and are not set forth herein.

What I claim is- A worm and a worm-wheel, a tooth of the worm being set in a curved plane corresponding to the curve of the circumference of the worm-wheel and having its driving or contact side varied along its length to assume different pitches relative to the axis of the worm and the teeth on the worm-wheel having their contact sides formed in a compound curved plane having a general oblique direction across the face of the wheel to correspond to the face of the worm-tooth, substantially as set forth.

JAMES F. WELOH. Witnesses:

FREDK. HAYNES, I. B. DECKER. 

